Estrogenic hormones have a marked effect on uterine growth. We will be studying three aspects of this system. A major effort is to complete the purification and characterization of the so-called IP protein of the rat uterus. Purification will permit us to prepare antibodies which in turn will be used in characterization of the protein. The second area we will study is the effect of estrogen on DNA synthesis. This will include characterization of the DNA polymerases found in nuclear and cytoplasmic compartments of the cell. The third area concerns the translocation of estrogen receptor into the nucleus. We will attempt to further characterize this process. BIBLIOGRAPHIC REFERENCES: Williams, D. and J. Gorski. Techniques for monitoring the distribution of the estradiol-binding protein complex between cytoplasm and nucleus of intact cells. In: J. G. Hardman, ed., Methods of Enzymology 36: 275-283, 1975. Stancel, G. M. and J. Gorski. Analysis of cytoplasmic and nuclear estrogen-receptor proteins by sucrose density gradient centrifugation. In: J. G. Hardman, ed., Methods in Enzymology 36: 166-176, 1975.